Traditionally, for example, an ion beam apparatus is widely used for the purpose of preparing a TEM sample that is used to observe defects generated in wafer fabrication processes of semiconductor memory and the like by a TEM (Transmission Electron Microscope) and the like. In this type of ion beam apparatus, ion beam fabrication by the focused ion beam (FIB: Focused Ion Beam) allows processing a micro-cross section for observation in a particular portion of a TEM sample, and allows preparing the TEM sample for a relatively short time.
However, when the traditional ion beam apparatus is used to perform ion beam fabrication for forming a micro-cross section in a sample, gallium used for an ion source of the focused ion beam is injected into the cross section of the sample to alter the sample amorphously, and gallium forms a damage layer which is a so-called fracture layer with the damaged cross section. Since the sample having this fracture layer formed on the observation cross section adversely affects relatively high-powered TEM observation by the fracture layer, there is a disadvantage that a normal crystal lattice image cannot be obtained, causing a problem in highly accurate observation up to the atomic level of the cross section. Therefore, the fracture layer needs to be removed so that the fracture layer of about 30 nm formed on the cross section of the sample is reduced up to about 10 nm.
Then, it is considered that the acceleration energy of the focused ion beam is reduced to decrease the thickness of the fracture layer, or that after fabrication by the focused ion beam, an ion beam of relatively low energy is irradiated onto the cross section to remove the fracture layer formed on the cross section. Furthermore, the ion beam for removing the fracture layer is irradiated onto the cross section to form a new fracture layer on the cross section as well. However, a fracture layer formed by using an argon ion beam, for example, is about a few nm, and thus it does not cause problems in observing the cross section.
Accordingly, for the traditional ion beam apparatus, an apparatus is proposed which has a removing beam part that irradiates an argon ion beam onto the cross section of a sample formed by irradiating a focused ion beam and removes a fracture layer on the cross section.
This traditional ion beam apparatus has a holder part which holds a sample, a processing beam part which processes a cross section in the sample, the removing beam part which removes the fracture layer on the cross section processed in the sample, and an observing beam part which observes the cross section of the sample. The holder part has a holder member which holds the sample on the tip end side thereof. The processing beam part is disposed vertically above as facing the top surface side of the sample held by the holder member. The removing beam part and the observing beam part are disposed at the positions to sandwich and face the cross section of the sample.
In the traditional ion beam apparatus thus configured, the processing beam part irradiates the focused ion beam from a gallium ion source onto the sample held by the holder member to process the cross section, and the removing beam part irradiates the argon ion beam onto the cross section of the sample to remove the fracture layer of the cross section (ion milling). Then, the observing beam part irradiates an electron beam onto the cross section of the sample where the fracture layer has been removed, and an observed image of the cross section of the sample is obtained.
In the traditional ion beam apparatus described above, as shown in FIG. 11, in irradiating an argon ion beam onto a cross section 104 of a sample 103, the argon ion beam is widely irradiated onto the area other than the cross section 104 of the sample 103. Therefore, the argon ion beam is irradiated onto a step part and the like adjacent to the base end side of the cross section 104 of the sample 103, and is partially irradiated onto the top surface and the like of the step part to fly or eject secondary particles of the fracture layer, causing a problem that the secondary particles of the removed fracture layer are again attached onto the cross section 104 and contaminate it.
Then, an object of the invention is to provide an ion beam apparatus, an ion beam processing method, and the holder member, which can excellently remove the fracture layer from the processed surface of the sample.